Redesigned Extruder
Earlier this year I experimented with a bowden cable style extruder and got mixed results, I mostly got loads of ooze and constant filament jams. So shortly after my upgrade to MK4 electronics I redesigned my extruder combining what I have learned over the past few designs.
Bowden Cable Style Extruder
I love MakerGear Groove Mount hot ends, they almost never fail and are easy to switch out for cleaning or repair. So I used my tried and true groove mount quick change block, you might be thinking "you can't make the groove mount out of ABS, it's gonna melt" well you would be surprised. The mounts hold up just fine and I haven never had one fail due to heat issues, many others have now embraced the printable groove mount.
Redesigned Extruder
I enjoyed the accessibility that I gained from the hinged idler bearing I used in the bowden cable filament drive, it did however have one flaw. One spring was not enough to apply proper tension to the idler bearing so the filament would often skip causing inconsistent extrusion widths. I redesigned the idler to allow for two springs so there would no longer be skipping, if the filament strips now it will be due to a blockage in the nozzle.
Twin Tension Springs
Orientation of the stepper motor was another feature of the bowden cable filament drive that I carried forward, it allows for unrestricted service access of the filament drive making it easier to clean out the gear teeth after a jam or to switch out filament. I plan on using this similar yet mirrored orientation of the stepper motor when I design my dual extruder.
Increased Service Access
I lined the filament path both top and bottom with 2mm ID Teflon tubing, I had noticed that the entry hole to the drive had started to widen due to the incoming filament. The Teflon tubing at the top of the drive will prevent the erosion issues, the Teflon at the bottom will prevent the filament from buckling when entering the hot end, I have cleared many jams that were caused by the filament buckling at the top of the hot end because of too much clearance.
Teflon Lined Filament Path
I've been printing with the redesigned extruder for about two weeks and have yet to have a single jam or stripped filament.
Matthew LaBerge






